


into deep waters

by fthh



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe, F/F, Fluff, I Don't Even Know, mermaid au
Language: English
Status: Completed
Published: 2020-06-30
Updated: 2020-06-30
Packaged: 2021-03-04 19:34:52
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,725
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25001731
Author URL: https://archiveofourown.org/users/fthh/pseuds/fthh
Summary: It’s quite funny, actually, to see Petra Macneary, huntress extraordinaire, the subject of legends, stumble (who knew mermaids were capable of such a feat?) because of a human woman with flowers in her hair.
Relationships: Dorothea Arnault/Petra Macneary
Comments: 4
Kudos: 45





	into deep waters

**Author's Note:**

> and for the last day of pride month, here's some doropetra!
> 
> (it's still June 30th somewhere, right?)

Petra is sensitive to her surroundings. She always has to be, especially this close to the surface. Her kind has been hunted for their scales, and besides, as a hunter, she  _ has _ to sharpen her senses anyway.

And so she notices the odd movement in the water. It’s not the wind — water responds differently to wind — this is something much more… solid.

Petra swims closer to the shore, and locates a figure at the end of the pier. She lets her eyes glow an eerie shade of yellow-green and unhinges her jaw to reveal sharp teeth, meant to ward off any predators (these days it’s mostly human poachers, she thinks disdainfully). Petra stalks closer, and—

Oh.

It’s a pretty woman with flowers in her hair, singing a song, barely above a whisper, watching the sun setting for the day.

Petra hurriedly swims away. It’s not until she’s in the privacy of her own room that she registers the rapid, irregular cadence of her heartbeat.

“My little dove, is everything alright?” Her Majesty the Queen asks. Petra isn’t making much progress with her dinner — she’s mostly twirling her noodles on her fork, staring off into the distance.

“Yes, Grandmother,” Petra answers quietly. She tries to be cheery, she really does, but she only ends up with a saccharine too-sweet smile that the Queen can easily see through.

Dinner goes by without another word from the young princess.

.

Petra spends the whole next day making a necklace out of seashells. She picks out brown, to match the woman’s hair colour, and pink and white, to match the flowers in her hair.

It’s silly. Petra doesn’t even know her name. Bernadetta thinks so. Bernadetta says so — right in her face, in fact. She’s the only member of the palace’s hunting entourage who can say these things.

She is Petra’s best friend, after all.

“I am asking whether you think she would like this necklace,” Petra reminds her, a little annoyance seeping into her voice. But she knows Bernadetta means well. She always does. Bernadetta was sculpted in love and compassion, even if she hides it in her shyness.

“I think…” Bernadetta pauses, considering, eyeing the necklace in Petra’s hands. “I think you should ask for her name first before you give her anything.”

Petra finishes threading the final shell, and leaves it in her drawer. She reckons she can trust Bernadetta with these things. She has a centauress lover, after all. Those dwell on land, and perhaps Bernadetta has more authority on these things than she does— Petra closes her drawer and forgets about it when she hears an attendant call on them for dinner.

.

The human woman is at the pier, again. This time she’s brought with her a mint blue-haired man and their voices travel as the man says something and the woman laughs at him. Petra’s heart sinks a little, but files away the woman’s laughter, the most beautiful sound she’s ever heard, and she’s friends with a few sirens.

Petra watches, still, from beyond the rocks. When the sun starts to set the man lies on his back and the woman starts singing, cheerfully, and truthfully Petra  _ should _ be alarmed at how absolutely captivated she is by the woman’s voice, but. She can’t find it in her to care. She’s singing about being left by her lover in the sunniest tone Petra’s ever heard — how can she not be fascinated?

Petra wonders for a moment if the brown-haired woman is a siren after all— she finds herself swimming closer, closer, closer…

“Petra!”

She startles at the voice, turns to its owner. It’s Bernadetta, coming up to her from the beach. She’s just returned with her centauress lover, who has stopped a few paces away from the shoreline. They’d had an outing on land for the day.

“I trust you had fun?” Petra asks, but she’s waving at the centauress galloping away with a spring in her steps. She winces when the centauress almost bumps into a tree, happily distracted.

Bernadetta doesn’t answer, only joins her best friend in the water. Once she’s submerged up to her hips, the water around them glows purple, the colour of Bernadetta’s scales, and her legs prickle as they always do when she turns back from her human form.

“Hey, what were you looking at? You were pretty distracted there.”

They both turn to the pier, only to find it empty. Petra cocks her head to the side, wondering how two  _ humans _ slipped by without her noticing, and at that moment her sensitive ears pick up the faintest sounds of footsteps — but there’s no mistaking it: there is weight being lightly pressed onto the sand near them.

Petra hones in on the footsteps as the soundwaves move easily through the water. She swims as fast as she can, following its direction. Once she’s close enough, she bares her sharp teeth and lets her eyes glow a ghostly green. Stalking beside her, Bernadetta pulls out a dagger from her pack.

“Hey, shh!”

Once Petra is close enough, she lunges forward, easily breaking the surface of the water, sharp teeth at the ready to attack the enemy. She pounces at them, and—

It feels like hours are passing, the way the enemy’s face is registering in her mind. It’s the pretty woman, with the flowers in her hair. Petra’s brain is screaming for her body to stop; her heart is plain  _ screaming. _

She flops unceremoniously to the ground. Very unbecoming of a huntress, or princess, or mermaid, she’s sure, but she has never been in this situation before. She does  _ not  _ want to accidentally bite a chunk off of a pretty woman.

Bernadetta, in her shock, stops her movement. “Petra?” She asks, her voice as small as Petra has ever heard in the years they’ve known each other.

When Petra looks up, wide green eyes are staring back at her, maybe in awe, maybe in fear of her life. She  _ did _ charge at them to kill, after all.

From this small distance between them, the woman is infinitely prettier. Her green eyes are positively  _ shimmering,  _ and she didn’t know human eyes could even do that. (Granted, she hasn’t much experience with land-dwellers, but the point stands.) The woman’s skin looks soft, and Petra wonders if human skin feels like hers.

So she reaches out— or at least, tries to. She can’t seem to move her hands, her limbs laying pathetically by her sides. She thrashes her tail wildly, seemingly her only body part that she has any mobility over. Petra can hear Bernadetta swimming towards the shore, albeit at a more cautious pace, assessing the situation. In the corner of her eye, she can see Bernadetta discreetly pulling up her dagger.

“We mean no harm,” the woman says. “We were just curious. I’ve noticed you watching me this past week.”

Petra finds the static fading away from her body, and she can move her arms again. When Bernadetta reaches her, weapon tucked away, she only sees an untamed blush forming against Petra’s features, visible even in the dim light of the sunset. She smiles. Petra only smiles back, sheepish, knowing for sure she’s heard what the woman said.

“Yes,” Petra says, sitting up, looking back at the woman, cheeks on fire. “I admit I have been watching you this past week. I must apologise for perturbing you; I was— am… fascinated.”

“Oh.”

“Hey!” The man’s voice is loud. “You’re the crown princess of Brigid, aren’t you? Wow, I never thought I’d see you in person! I’ve heard stories about you! Oh, Dorothea, this is so cool! Thanks for dragging me with you!”

Bernadetta, childhood friend, current best friend, almost always by Petra’s side,  _ gapes _ at the way the princess is at a loss for words. Bernadetta has seen Petra not even so much as flinch at foreign dignitaries of countries much bigger and more powerful than Brigid.

And yet, here she is, tongue-tied, for the first time in her life, flushing red in front of a human woman.

“I— We— So long!”

Petra jumps the short distance to the water, and swims away with Bernadetta in tow.

The two humans only watch after them.

.

The next day, the woman seems to be expecting her. Looking for her, even. Petra sees her figure at the end of the pier, watching the water around her with rapt attention and waving at her once they spot each other.

Petra, unsure, points to herself and the woman nods, waving more enthusiastically. Not one to say no to a pretty girl, Petra swims over with a silly grin adorning her features, one that is mirrored by the pretty brunette.

“You have very pretty scales,” the woman says in place of a greeting, and it’s almost like Petra has forgotten her entire vocabulary by the way she’s gaping, wide-eyed, floating in the same spot. “Where are my manners,” the woman laughs, “my name is Dorothea.”

“P— Petra. Macneary.”

“Caspar told me stories about you. He wouldn’t shut up all night. It was cute, if I’m being honest.”

“Caspar,” Petra echoes. She doesn’t mean to sound dejected, she really doesn’t — it’s their first official meeting after all, and she doesn’t want her first impression to be  _ moody mermaid princess  _ — but she can’t help the disappointment in her voice. Her grandparents have always said that she’s an honest mermaid. After a few beats, she asks: “Your beloved?”

Dorothea hides a giggle behind a hand (very cute, if Petra may say so herself). “I  _ do _ love him, but as a brother. And I don’t swing that way, if you know what I mean.” Dorothea raises a conspiratorial eyebrow.

.

“Oh, Bernie, she is a dream,” Petra rattles off, as she has been for the last five minutes, “We talked for hours! She said she was a witch, and sparks came out of her fingertips! She is accompanying her mother on tour, and the boisterous man from yesterday was her brother. He wished to come along but she said family meetups are for after the tenth date. I hope she meant it in a romantic manner.”

Bernadetta messes the movement of her quill. She will have to start her drawing anew, but right now there is a more pressing matter: “Petra, you can not be serious?”

.

It’s a funny sight, really. Fearsome huntress, Petra Macneary, next in line for the Brigid crown… in the library surrounded by books about cooking, only because the human woman,  _ Dorothea,  _ said she couldn’t cook for shit.

“Do you think she would like my seaweed cookies?” Petra asks without looking up. She can sense, of course, Bernadetta swimming towards her, pensive, maybe? Definitely a hint of bemusement there, Bernadetta biting down on her lip to stop herself from smiling.

Petra bakes three batches of cookies, because the first two just aren’t up to par, whatever that means, because they taste the same to Bernadetta: a perfectly acceptable balance of spice and sweet. (Petra has never claimed to be the best cook and Bernadetta isn’t about to needlessly inflate her ego.)

Dorothea’s expression contorts as she lets the cookie sit on her tongue, rapidly figuring out whether or not she likes the taste. “This…” she tries, tilting her head to the side. “I  _ think  _ I like it?”

Petra smiles, hoping to the Spirits that her body language doesn’t betray her nervousness: she squares her shoulders, back straight, her tail playing with the water where they touch.

“Hm,” Dorothea makes a cheery sort of sound. “Is that… honey?”

“Yes! I harvested it myself, yesterday.”

“You have honey bees underwater? That’s amazing.”

“Oh, no,” Petra laughs. “Bernadetta’s lover maintains a bee farm on land. She lets me have some, on occasion.”

“On— land?”

“Ah. We have business on land sometimes. I can grow legs at will. Most of us are able to.”

Dorothea watches her, biting her lip to suppress a teasing smile. The mirth in her eyes is apparent, the green colour glinting in the sunlight, and a small laugh escapes her lips. (Petra will not admit she’s watching Dorothea’s mouth intently, no matter how much she’s pressed on the matter.)

“What?” Petra asks.

“I was just wondering,” Dorothea says, all coy and ribbing, “if you were shorter than me, if you had legs.”

“I—” Petra starts, faux-indignant, playing along with Dorothea, “I most certainly am not!”

“Oh yeah?” Dorothea taunts, standing up to her full height.

With a flick of her wrist Petra’s tail starts glowing and she grows her legs, and at once she stands up against Dorothea, and— oh. She  _ is _ shorter. Petra snorts at that.

Except she belatedly realises she’s standing chest-to-chest with Dorothea, and she is as naked as she can possibly be, and Dorothea does not know where to look because her eyes are looking everywhere except for her and—

Petra jumps into the water, and finally Dorothea looks at her again. She hopes she isn’t imagining the redness of Dorothea’s cheeks.

“Well,” Dorothea says, tries for a confident tone, but her voice is wavering. “I guess we figured  _ that _ out.”

.

Petra watches sunsets sat next to Dorothea, now. It’s become a routine for her: royal duties in the morning, training or hunting in the afternoon, and then spending the rest of her time with her new human friend. (She wants more, of course, but… one step at a time.)

She doesn’t say anything about the way Dorothea insists on sitting next to her as close as possible, not minding the fact that she gets damp where they touch. Petra would like them to stay like this well into the night; more often than not, however, much to her chagrin, their meetings are cut short.

(“Reality calls,” Dorothea would say wistfully when Petra says she has to go for dinner with her grandparents.)

.

Petra feels like she’s running against time in a race she won’t ever win.

She’d always known, in the back of her mind, that this thing with Dorothea won’t last forever. She’s only here to accompany her mother on tour.

“I wish I could see Brigid with you. It seems like a pretty place.”

“Me, too.”

They fall silent, again. Petra’s hands are busy running through Dorothea’s soft tresses, arranging locks of hair into intricate braids. She wonders if Dorothea’s shivering is from her touch or from the cold air.

“We could visit the sea witch. He has done plenty of transformation spells,” Petra suggests hopefully, pausing her ministrations.

Dorothea seems to think it over, silent for a few moments.

“Let’s go.”

.

“Oh good. The princess is here.” The man says, deadpan, walking back into his home.

“It is very good to see you as well, Linhardt.”

He sighs, and takes a moment to collect himself as he lies back on his chaise longue. Dorothea startles at the sight of his green tentacles. Petra takes her hand and they sit across from Linhardt, but her eyes never leave the strange sight.

He sighs.

“I suppose you’re curious how I became this way? Very well. I was cursed for sleeping in the previous sea witch’s bed. In my defense, her bed was very comfortable and she hadn’t been home in two months.”

Dorothea stays silent, and it’s Petra who speaks for the both of them: “I would like to take my… friend here to Brigid for sightseeing.”

“Oh? Like a date?”

“Uh—”

Petra prods at Dorothea’s side. “Yes, something like that.”

“Well,” Linhardt claps his hands together. “Who am I to stand in between young love?”

Petra doesn’t mention the fact that he is, in fact, only a year older than her, only takes the vial Linhardt hands her.

“And my debt to you?” He asks.

“Consider it paid.”

“Oh, and Petra?” He says as the two women reach the door, eyeing the both of them intently. “There’s a more… permanent spell, but it requires sacrificing your most prized possession.” He pointedly looks at Dorothea. “Just some info for you two.”

.

Dorothea waves her new tail in wonder, the sensation of not having two separate legs new to her.

“This is fascinating,” she says in awe.

The two of them swim at the surface for a bit before Petra takes Dorothea’s hand and brings her under. They linger for a few moments, Petra letting her freshly-developed gills acclimate.

“You can inhale,” Petra says, laughing.

Dorothea, skeptical, does so, eyes wide in surprise upon finding out she isn’t choking on water. “This is— Petra! I can speak!”

The candid glee is irresistible to Petra. She leans forward, tipping Dorothea’s chin slightly and—

“I am sorry. I do not know what came over me.” Petra tries to back away, but Dorothea is instantly on her, grabbing both of her arms so that they’re touching again. “I—”

“I  _ want _ you to kiss me,” Dorothea says simply.

So she does.

.

They break away, eventually. Petra takes her farther and farther from the surface until finally they see the gates leading to Brigid.

“Welcome to my home,” Petra says gleefully, hand holding onto Dorothea’s firmly.

“It’s so beautiful!”

Directly inside the gates is a pathway leading to gardens, different stalls lining it as far as the eye can see. From a cursory glance, they seem to be vendors of trinkets and food.

Petra takes her to see the palace, to visit the seahorses. She is introduced to Petra’s pets, Echo and Wave, and finds out that seahorses are small and bony. She is whisked away to the pantry to pack some snacks and they camp out at the gardens near the gate. Dorothea finds that she likes the mixed sweet-and-salty flavours that Brigidians seem to be fond of. They watch citizens mill about, once or twice their conversation paused to greet children.

(Petra doesn’t let go of Dorothea’s hand even for a second. She’ll take that as an accomplishment.)

When the sun starts to set, Dorothea is invited to the palace.

“What, am I really meeting your grandparents on our first date?” Dorothea asks, playful.

“I believe you said family meetings are for the tenth date,” Petra fires back. “I was wondering if you would like to spend time… in my room.”

“Ooh, very forward. I like that.”

.

Petra pins her to the wall as soon as the door is closed behind them. She kisses Dorothea fervently, and in her excitement accidentally bites down on her lips.

“I—” Petra pulls back, but Dorothea chases after her and kisses her with more earnestness, sliding her own tongue between Petra’s lips. She’s happy to be welcomed enthusiastically.

Petra takes the lead once again, pressing kisses onto the side of Dorothea’s face, down her neck, and then back on her lips. She leads Dorothea to the bed. In their hurry, they knock Petra’s nightstand and its contents clank loudly.

They break apart and laugh at the ridiculousness of the situation.

They don’t do much else than talk and kiss throughout the night, and in the morning Petra sends her back off to land.

.

They still spend most of their time at the pier, away from curious eyes. Rumours have circulated about the new face in town, and Petra doesn’t want to give anyone ideas, especially since this isn’t a permanent thing.

They’re just having fun.

They’re just having fun.

They’re just having fun, and yet… Petra longs for so much more.

.

Petra makes good on her promise, as jokingly as she’d said it the first time. It’s just the three of them tonight, what with the King away on business. She’d invited Bernadetta, too, but she had prior plans with her lover, so.

“So… you are the human woman my granddaughter has been seeing?”

The Queen’s voice is warm and inviting, while still keeping a distance. Petra wonders how her grandmother pulls it off.

“I’m a witch, if that makes any difference.”

“Oh? Any specialties?”

“Lightning, ma’am.”

The Queen breaks into a smile. “My first love was a lightning witch, much like you. Tell me, child, what brings you to this part of the world?”

“My mother is on tour. I’m accompanying her with my brother.”

Reality dawns back on her, that this is all temporary, but she manages to put on a smile and enjoy the night with Dorothea and her grandmother. The two take to each other like a house on fire. It’s wonderful to see. Petra’s heartstrings tug at the sight.

.

“I... I have to go back to Enbarr soon,” Dorothea breaks the silence between them. They’ve been sitting at the pier, watching the moon and its wavy reflection in the water.

Petra traces a finger over Dorothea’s arm, watching goosebumps form. It fascinates her that this is happening, even in the heat. She makes her decision, then.

“I hope I can see you again,” she says quietly, leaves  _ I want to see you again, I hope you stay _ unsaid.

“Well, Manuela’s going on tour again next year.”

“Forgive me for being blunt, but that is far too long, Dorothea.”

Dorothea smiles at her. “Yes,” she acknowledges. “Entirely too long, but I have things I need to take care of, there.”

Petra produces a seashell necklace from her pack, and hands it to her. “For you to remember me by, when you are back home.”

The silence falls upon them, again. Petra looks at her, just  _ looks,  _ memorising the curve of Dorothea’s cheeks, the dip in her clavicles, the sharp angle of her chin, the softness of her skin.

“Is Enbarr landlocked?”

“Uh— no?”

“Well then, I shall see you in a few weeks,” Petra chirps. Dorothea seems to be buzzing with excitement, and hugs her. When she leans back, she doesn’t let go, only eyes Petra’s lips keenly.

Petra jumps back when her lips finally touch Dorothea’s. Her lips are tingly with static and her heartbeat is thundering in her ears, except…

There’s real lightning behind Dorothea, and she can  _ feel _ the electricity expanding the air around them, along with the accompanying low rumble of thunder. Dorothea’s hands are alight with sparks — she immediately hides her hands behind her.

“I— this happens when I’m excited! I’m so sorry!”

Petra leans on Dorothea’s shoulder and they talk and talk until Dorothea calms down. When Dorothea kisses her for the second time that day, Petra’s lips feel all tingly again, but this time for entirely different reasons.

**Author's Note:**

> petra visits every few months and after years of ldr dorothea brings her silver mittelfrank brooch to the sea witch to sacrifice it and become a mermaid. the end.
> 
> also if you were wondering why absolutely nothing made sense that's because it doesn't! sometimes logic just has to take a backseat to self-indulgence luvs
> 
> [x](https://twitter.com/clonebutt)
> 
> (i'm gonna take prompts soon, i think)


End file.
